Phonograph-shock and vibration absorbing support



29, 1950 R. M. CAIN 2,520,757

PHONOGRAPH-SHOCK AND VIBRATION ABSORBING SUPPORT Filed Jfine 15, 1946 INVENTOR. ROBERT M. CA/N Patented Aug. 29, 1950 UNITE RATE-NT ,eaoneeneenesnocn AND vmRATieN ABSQ g SUP QR v "*fRobertM.-Cain;- Ghai'iotte, Micln; assignortotWilccx-Gay GoI-Poration, Charlotte, Mich acor- =peratio'nof'ltiichigan a Application June lfi, 194,6,s a1-no.;6j76,ss9

. l My invention relates'to sound'apparatuspand more particularly to a mounting means for. the lbase'plateiof a phonograph or other device, "which jmdunting will avoidmicro'phonism between \elements of the phonograph andthe loud speaker, andwhichwill also serve to absorb other physical ishock's or Vibrations.

TfHeretiofore one of the problems which arose in connection with phonogrjaphsmounted in" cabin'ts is'th'at'the vibrations transmitted .fromthe loudspeaker through the cabinetto' the pickup arm o'f' the phonograph :tend edto-result in "the production of microphonicnoises.

.Inran attempt-to avoid suchfmicrophonismrthe picktup arm of the phonograph was resiliently mounted orits post'was spaced by a shock absorbiing grommet from the mounting plate. This, however, introduced unforeseen lateral and vertical compliance in the pick-up arm' mounting which interfered substantially with the "efficiency of the pickup arm. Someof the vibrationstrans- ;n1itte'd to the pickup needle-by the reoordwere fabsorbed even before they could reach the pick up-crystalpr other pick-up unit owing to 'th'e f-act ithatthe pick up unit itself could move slightly flaterallyand -was able to twistslightly in a ver- "tifoahplane. f 7

Myinvention provides a novel means for mounting the entire base-plate of the mountin'g *unitso that all-of the elements" thereof'ar'e ins ulated'mechanic'ally from the cabinet which contains the loud speaker. T

invention specifically contemplates-novel "mounting means for the base plate'of a phonograph or other-support for the pick up;:arm, cuttingarm and'other'elem'ents of the phonograph which'-mounting means is capable of absorbing both vertical 'and 'horizon't'al shocks and "vibrations as Well as shocks and vibrations in other planes.

A primary object of my invention therefore *is the provision 'of a shock-absorbing mounting for the base plate of a phonograph orother "similar unit.

"s nnotner object of my invention is the arrange- -ment of a grommet mountinginsuch a-manner that lit" may readily: absorb horizontal'sand': vertical vibrations; as well 'as vibrations in planes at angles thereto.

A further object of my'inventionis-the prowision of a force-distributing grommetmounting m'eans so arranged that it will yield to varying degrees in response. to shocks or vibrations of v aryinga intensity x yielding. progressively? "1703 a greater degree as the shocks o1.- fvibrationslbecome rmoreeintense.

4' Claims. (01. 243- 22) "This is distinctly different from the ,usualig'rom- (met arrangement; in which the compressibility curve'fiattens out as greater shocks or vibrat ons are encountered.

The foregoing, and many, other objects pir my invention "will becomeiapparent in the' following descriptionmand drawings in which "Figure lis a top plan View of a mountingplate jofj a. phonograph showingmy novel mounting; 10

I "Figure 2 is a crossesectional view taken on! line 1 $2 2 Off Figure 1.

.acentral cylindrical hole 38 extending-from -th surface:.33f'ltorsurtace -34; along; the; axisipfnthe Figure '3 is. an. expanded iew of the hotel mountingdevice of' Eigure'2. j

, Figure 4 is a schematicfdiagram showing.jthe

.force Jdist'ributioh on the. grommet 01". my novel mounting idevice.

L'Ihe operation of their-turn vstable is. controlled by the switch knob, i5. 'The phonographherefshown is'of the typegenerallyillustrated in'Pate'ntNo.

235L948 which isv assigned to the assignee offthe present invention;

The base plate It! is mounted in the top ;-,o f acabinet and is supported at .the topof "the cabinet vby my novel vibration-damping .shockab'sorbing mounting means 26, 20, which', in this case.

,arezshoi vnyatueach of the corners. ofjthe ease vplate.

The m0unting -2l1 asS1t10Wn in EiguresLZ and 3 which secures the base plate iii to ,thetop 2 I of the cabinet comprises a bolt 25 of sufificient length ,to pass from the upper side of base. plate a l 6, --.to substantially; below the: under-side of ;.the top member 2! ofv the cabinet; awwasherlfimia rubber grommet 2-1 and aspecially shapedhsleeve 2.8,a Washer 29;-andfa-n ut 31).

The: rubber grommet. 21- as shownjin Figures :2. and 3 is a substantiallycylindricalmemberhav ing parallel plane qppositeends 33,: 34% anditan annular groove 32 adjacent theuppersurfaceQB of. the grommet :21. The base plate I0: is p :Vidfid with a circular-opening 35vateachofAihe corners andgthe: grommet. '2'l ,iis placedintoiihe iopeningyso that-ithev material ofbasemlate; 'Hl defining-1. the, opening 35 is receiyed; in the .anpnulanzgroove ,32 as shown in Figure 2. 7

i The ronunet; 2 i also. as shown in Figure 2, has e The bolt 25eismassedlthmy brthei neninaQ39 in washer 26 and then is passed down through the central opening of the grommet.

The sleeve member 28 is then passed up over the lower end 40 of the bolt 25 so that the extension 4| of the sleeve member 28 enters the cylindrical opening. 380i the rubber grommet 21. For this purpose, of course, the sleeve 28 is provided with a cylindrical central opening 43 of a sufficient size to receive the bolt 25 so that the bolt 25 may slide longitudinally with respect thereto and need not be threaded therein. 7

The extension 4| of the sleeve member 28 is of less diameter than the cylindrical opening 33 of the grommet. The base 45 of the sleeve'28 is of a diameter substantially equal to that of the grommet as shown in Figures 2 and 3 and the upper surface 46 of the base 45 is substantially conical in arrangement.

The sleeve 28 has an intermediate portion 56 between the narrow extension 4| and the base 45; the said intermediate portion 50 being so dimensioned that-it will be a close fit in the lower ofthe base plate II) and the bolt 25 and washer 26 in place as shown in Figure 2 and also with the sleeve 28 in the pcsitionshown'in Figure 2 The cooperation of the lower flat surface 34 with the conical surface 46 of the base 45 of the sleeve 28 permits the grommet 21 readily to absorb any vertical shocks or vibrations and permits the grommet also to twist slightly at an angle to the perpendicular to absorb shocks and vibrations in other planes. 7

The'cooperation of these two elements: The spacing of sleeve portion 4| from the side of opening 38 of the grommetand the co-action of the fiat surface 34 of the grommet with the conical surface 45 of the sleeve thus permits the absorption of shocks and damping of vibrations in both the horizontal and vertical planes and in at the .various corners of the mounting plate I0, the mounting plate I8 is then placed on the cabinet so that the ends 48 of each of the bolts *at each of the corners registerv with the open-v ings 52 in the top member 2| of the cabinet.

Theimounting plate It is then lowered so that the ends 45 of each of the bolts 25 passes through the openings52 in top member 2| 'of thecabinet some under-side of the said top member 2|.

The washer 28 is then placed over the ends 49 of the bolts 25 and the nut is tightened against 'the washer pulling downthe bolt 25 and tightening the washer 26 against the upper surface 33 of the grommet.

With the mounting plate I8 in place as shown in Figure 2, the load of the mounting plate on each of the grommets 21 causes the lowered surface 34 of each of the grommets to be deformed into a'substantially hollow conical form match- V The ability of the grommet 21 to absorb shocks and damp vibrations'both horizontally and verti- 'cally as well as in planes at angles thereto is determined by the conical basesurface 46 and by the height of the section 58 of the sleeve'which just fits the cylindrical central opening 38 of the grommet 27. 'Ihis cylindrical portion 58 should be relatively short having only sufiicient flength to ensure that the sleeve 28 will be centralized with respect to the cylindrical opening 38 of the grommet 21; while the extension of the sleeve 28 is of much less diameter than the cylindrical ope'ningtfi of the grommet 21.

It will thus be seenthat the portion of the grommet 27 in the region-of the annulargroove I l which engages the opening 35 0f 'the'base plate Ii! is free to move laterallyand even to twist slightly in a plane at an angle to the horizontal and thus to absorb any horizontal. shocks or vibrations 'or any other shocks or vibrations in 7 planes at an angle tothe horizontaL- planes at angles thereto.

The utilization of four such grommets and their associated elements at each of the four corners of the base plate I0 thus serves to physically insulate the base plate II] from the remainder of the structure beneath the top surface 2| of the cabinet.

Microphonism between the loud speaker or other portions of the device within the cabinet and the pick up arm, cutting arm or turn table are thereby completely avoided. V In Figures 5 and 6, I have shown them'odified form |2'| of .the grommet and amodified form I23 of the sleeve which operates in the same manner as that described in connection with Figures 2, 3 and 4.

The annular groove I32 of grommet I2! is received in the opening 35 of base plate It. The sleeve I28 is mounted through the lower end I50 of opening I38 of the grommet in the manner alreadydescribed in connection with the similar structures of Figures 2 and 3. The bolt 25, washer 2E, washer 29 and nut 30 are utilizedin exactly the same manner in connection with the construction of Figures 5 and 6 as has already been described in connection with the prior fig:- ures. The extension I4I of the sleeve I28 is spaced from the side of the central opening I38 of grommet i2? by the narrower communicating opening I50 at the lower end ofthe grommet.

It will thus be seen that with the sleeve I28 in place in the grommet, the side of the opening I38 is spaced from the sleeve for the purposes previously described in connection with the spacing of the extension ofthe sleeve 28 of Figures 2 and 3 from the inner surface of the opening 38 in the grommet 21. ,1 a

The grommet of Figure 5 and the base plate mounted thereon may thus readily absorb shocks and damp vibrations in a lateral or horizontal direction; The lower surface I34 of grommet I28 is conical in form as shown, while the upper surface fiat. e V V 7 When a load similar to the load previously described is placed on the grommet I21, the lower surface I34 thereof is'deformed and tends to be' on the other hand may be combined, thus the grommet 21 of Figure 2 may be used inconnection with the sleeve? of the typeof sleeve 28 of Figure 3 omitting, however; the side portion 58.

of sleeve 28 and substituting in placeithereof. the

I46 of extension I45 of the sleeve I28 is a .5 smaller opening I56 of grommet l2! in the lower end of cylindrical opening 38 of grommet 21.

The essential element is that the grommet be so formed that it may readily yield to and damp the effect of shocks and vibrations in both vertical and horizontal planes as Well as in planes at angles thereto.

It will thus be seen that the grommet is relatively stiff for shocks and vibrations of low intensity; but that as shocks or vibrations become more intense, the grommet becomes relatively more flexible with respect t ereto and offers a greater degree of resilience to absorb the same. This is the contrary of the result achieved with the usual compressible grommet which if compressed and becomes less resilient as the intensity of shocks and vibrations increase.

In the foregoing, I have described my invention solely in connection with a specific preferred embodiment thereof. Since many variations and modifications of my invention should now be obvious to those skilled in the art, I prefer to be bound not by the specific disclosure herein contained but only by the appended claims.

I claim:

1. A shock and vibration absorbing support; said support comprising a resilient grommet; means for connecting an upper portion of said grommet to a load to be supported; a base unit against which the lower end of the grommet rests; said grommet being compressed between said load and said base unit; the lower surface of said grommet and the upper surface of said base unit being originally non-parallel surfaces; the lower surface of said grommet being compressed by said load to conform to the upper surface of said base unit; said grommet having a central opening; a central extension from said base in said opening of said grommet; and means spacing said extension from the interior of the surface of the opening in said grommet.

2. A shock and vibration absorbing support; said support comprising a resilient grommet; means for connecting an upper portion of said grommet to a load to be supported; a base unit against which the lower end of the rommet rests; said grommet being compressed between said load and said base unit; the lower surface of said grommet and the upper surface of said base unit being originally non-parallel surfaces; one of said surfaces being convex and the other of said surfaces being flat; the lower surface of said grommet being compressed by said load to conform to the upper surface of said base unit; said grommet having a central opening; a central extension from said base in said opening of said grommet; and means spacing said extension from the interior of the surface of the opening in said grommet.

3. A shock and vibration absorbing support; said support comprising a resilient grommet; means for connecting an upper portion of said grommet to a lead to be supported; a base unit against which the lower end of the grommet rests; said grommet being compressed between said load and said base unit; the lower surface of said grommet and the upper surface of said unit being originally non-parallel surfaces; one of said surfaces being convex and the other of said surfaces being flat; the lower surface of said grommet being compressed by said lead to conform to the upper surface of said base unit; said grommet having a central opening; a central extension from said base in said opening of said grommet; and means spacing said extension from the interior of the surface of the opening in said grommet; said last mentioned means comprising a widening of the portion of the extension immediately adjacent the upper surface of said base.

4. A shock and vibration absorbing support; said support comprising a resilient grommet; means for connecting an upper portion of said grommet to a load to be supported; a base unit against which the lower end of the grommet rests; said grommet being compressed between said load and said base unit; the lower surface of said grommet and the upper surface of said base unit being originally non-parallel surfaces; one of said surfaces being convex and the other of said surfaces being flat; the lower surface of said grommet being compressed by said load to conform the upper surface of said base unit; said grommet having a central opening; a central extension from said base in said opening of said grommet; and means spacing said extension from the interior of the surface of the opening in said grommet; said last mentioned means comprising a constriction of the opening in the grommet immediately adjacent the lower surface thereof.

ROBERT M. CAIN.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,587,484 Holden June 1, 1926 1,935,262 Chamberlain et a1. Nov. 14, 1933 2,024,728 Galson Dec. 17, 1935 2,195,873 Lord et a1. Apr. 2, 1940 2,223,028 Dobson Nov. 26, 1940 2,297,483 Kuhne Sept. 29, 1942 FOREIGN PATENTS Number Country Date 103,226 Australia Feb. 8, 1938 

